GraceDuration

GraceDuration(nominal: Duration, on_beat: bool = False)

A notated duration that takes no metrical time: a grace note.

nominal is the symbol written (an eighth, a sixteenth); the width of the event in its line is zero, so a run of grace notes adds nothing to the length of a line, and a grace note stays in the NEXT chain like any other event. How much time it actually steals, and from which neighbour, is a matter of realization, outside core.

on_beat records the semantic distinction that notation marks with a slash: False for the acciaccatura (before the beat, stealing from the preceding note), True for the appoggiatura (on the beat, stealing from the note it decorates).

Like every Measurable, a grace compares and hashes by its length, which is zero, so all graces are equal to each other and to ZeroDuration; compare nominal to tell them apart:

>>> from openmusickit.systems.wsmn.temporal.symbols import quarter, eighth, sixteenth
>>> GraceDuration(eighth) == GraceDuration(sixteenth)
True
>>> GraceDuration(eighth).nominal == GraceDuration(sixteenth).nominal
False
>>> quarter + GraceDuration(eighth) + GraceDuration(sixteenth) == quarter
True
>>> GraceDuration(eighth).temporal_system.name
'Western Standard Music Notation'
>>> GraceDuration(eighth).scale(2)
GraceDuration(MetricalDuration(1, 4))

Attributes

Name	Description
`__slots__`
rational_length
nominal
on_beat
temporal_system

Methods

Name	Description
`__eq__`
`__lt__`	Shorter than `other`, by rational length, within compatible systems.
`__hash__`
`__neg__`
`__sub__`	`self + (-other)`: the difference of two durations, in whatever notation it takes.
`__add__`	Zero plus any Duration is that Duration, of any system.
scale	Scales the notated symbol; the width stays zero.
`__radd__`	A grace is absorbed by whatever is on its left, `sum`’s starting 0 included.
`__repr__`

`eq`

__eq__(other)

`lt`

__lt__(other)

Shorter than other, by rational length, within compatible systems.

>>> from openmusickit.systems.wsmn.temporal.symbols import quarter, dotted_quarter
>>> quarter < dotted_quarter, dotted_quarter < quarter
(True, False)

`hash`

__hash__()

`neg`

__neg__()

`sub`

__sub__(other)

self + (-other): the difference of two durations, in whatever notation it takes.

>>> from openmusickit.systems.wsmn.temporal.symbols import half, quarter
>>> half - quarter, quarter - half
(MetricalDuration(1, 4), MetricalDuration(-1, 4))

`add`

__add__(other: Duration)

Zero plus any Duration is that Duration, of any system.

>>> from openmusickit.values.time.clock_time import ClockDuration
>>> ZeroDuration() + ClockDuration(5)
ClockDuration(microseconds=5)

scale

scale(scalar: int | Fraction)

Scales the notated symbol; the width stays zero.

>>> from openmusickit.systems.wsmn.temporal.symbols import grace_eighth
>>> grace_eighth.scale(2)
GraceDuration(MetricalDuration(1, 4))
>>> grace_eighth.scale(2).rational_length
Fraction(0, 1)

`radd`

__radd__(other)

A grace is absorbed by whatever is on its left, sum’s starting 0 included.

>>> from openmusickit.systems.wsmn.temporal.symbols import grace_eighth, quarter
>>> sum([grace_eighth, quarter, grace_eighth])
MetricalDuration(1, 4)

`repr`

__repr__()